1. Technical Field
The present invention relates generally to the field of rigid-rod polymer analogs and specifically to the field of multidimensionally crosslinkable benzobisazole polymers and processes for making such polymers.
2. Prior Art
The rigid-rod aromatic heterocyclic polymers are well known for their outstanding mechanical and thermal properties. These polymers can be processed into fibers or films with high tensile strengths and moduli, but they have relatively low fiber axial compressive properties compared to carbon fiber and inorganic fibers. The characteristically low compressive properties limit their potential applications in certain structural composites.
Molecular crosslinking has been attempted to enhance the compressive properties of rigid-rod polymer fibers. Several crosslinkable rigid-rod polymer systems, such as methyl pendent rigid-rod polymers (Tsai et al, U.S. Pat. No. 5,001,217), halogenated rigid-rod polymers (Sweeny, U.S. Pat. No. 5,100,434) and benzocyclobutene rigid-rod polymers (see Dang et al, ACS Polymer Preprints, Vol. 36, No. 1, pp. 445-456, 1995), have been accordingly designed to enhance the fiber compressive properties. Improvements in fiber compressive properties are apparent in certain systems as the degree of crosslinking increases.